A one pot synthesis and evaluation of 13-oxo-quino[3,4-b]carbazol-N-oxides as antimicrobial agents.

1-Oxo-1,2,3,4-tetrahydrocarbazoles (1a-e) upon mixed aldol condensation with o-nitrobenzaldehyde (2) yielded 13-oxo-quino[3,4-b]carbazol-N-oxides (3a-e). All the prepared compounds were characterized by elemental and spectral analysis. A plausible mechanism for the formation of the final products is proposed. The title compounds proved to have great potentialities as antibacterial and antifungal agents due to the presence of the N-oxide group. Particularly, the chloro substituted derivative, 3d, showed excellent antimicrobial activity.